I looked on their POEA website and this comes up so they are listed..
Perhaps others here will know more about them.
BISON MANAGEMENT CORPORATION Service Contractor
GF,2F&3F(LW) BMH CTR 3963 YAGUE ST STA CRUZ MAKATI
Tel No/s :  8964667 TO 69 / 7297124
Email Address :  info@bisonph.com
Website :  www.bisonph.com
Official Representative : MARITES A. CAMILOSA
Status : Good Standing
License Validity : 12/20/2010 to 12/19/2014